Firewood boiler

ABSTRACT

The present invention relates to a firewood boiler, comprising: a boiler main body including a feeding hole through which wood fuel and air for combustion are fed, a smoke exhaust hole defined in the top thereof so as to be connected to an exhaust pipe, an air inlet defined adjacent to the smoke exhaust hole, and a heating-water store in which heating water is stored; a main opening/closing unit installed on the boiler main body to open and close the feeding hole and selectively supply and block the entry of outside air into the boiler main body when the feeding hole is closed; an auxiliary opening/closing unit for supplying outside air into the boiler main body when the entry of outside air is blocked by the main opening/closing unit; a temperature sensor for sensing the temperature of the heating water; and a control unit for controlling the inflow and blocking of air by means of the main opening/closing unit on the basis of information on the temperature sensed by the temperature sensor. The heating water store is integrally formed along the entirety of the boiler main body, and the auxiliary opening/closing unit maintains a pilot flame for the wood fuel by supplying outside air into the boiler main body when the main opening/closing unit blocks the entry of outside air. Thus, a firewood boiler may be provided that can be safely used for a long period of time without extinguishing a pilot flame.

TECHNICAL FIELD

The present invention relates to a firewood boiler, and in particular to a firewood boiler which is configured to generate a heat energy using woods as a main fuel.

BACKGROUND ART

A boiler has features in that it heats water of a room temperature using a combustion heat generating as an energy source combusts, and the thusly heated water circulates along a pipe embedded in the indoor floor, thus heating the floor or the heated water can be used for the sake of a hot water supply. Depending on the energy source combusted so as to obtain the heat energy, there are an electric boiler, a gas boiler, an oil boiler and an oil-shared electric boiler having the advantages of oil and gas.

For the gas boiler, the electric boiler and the oil-shared electric boiler, it is easy to control the functions of ignition, combustion and fire extinguishing, so they are widely used for household and facility purposes.

In recent years, the energy prices of electricity and oil continue to increase, and in case of Korea, most of energies are imported from abroad owing to the lack of energy resource, the uses of such boilers might result in a higher economic burden.

Therefore, the developments of alternative energy are widely performed. As one of such developments, there is a firewood boiler configured to use wood which can be easily obtained from around us at a lower cost.

The above-mentioned firewood boiler has the problems in that it is impossible to freely supply the energy source and stop the supply of it like electricity and oil due to the combustion characteristics of the wood which is a main energy source, and it is hard to control the ignition, combustion and fire extinguishing.

In order to improve the above mentioned problems, a firewood boiler is developed, which can control the supply of air during the combustion of wood; however even though the supply of air is controlled, it is still hard to control the ignition, combustion and fire extinguishing depending on the kinds of woods, the thicknesses and sizes of the woods, the content of water of the woods, the preservation period of the seed of fire, and the tendency of a user.

It is hard to determine a proper amount of oxygen which is needed to keep the seed for ignition fire living for the sake of the following combustion after the fire is extinguished, so the seed of fire might be dead, which makes the re-combustion impossible. Unnecessary combustions might occur due to the oversupply of the oxygen, so the overheating might occur or the fuel might be meaninglessly consumed.

Since the heat energy generating as the woods are combusted is discharged to the outside by way of a stovepipe, the loss of energy increases, and the power of fire is not easy to control, so there are many problems in maintaining the temperature of the stored hot water in the boiler constant.

DISCLOSURE OF INVENTION

Accordingly, the present invention is made to improve the problems encountered in the conventional art and it is an object of the present invention to provide a firewood boiler which can efficiently prevent the seed of fire from being extinguished and can efficiently prevent the over combustion by controlling the amount of supply of oxygen.

It is another object of the present invention to provide a firewood boiler which makes it possible to enhance a heat efficiency of an energy which generates during the combustion of woods and which can be used long, and the temperature of the stored hot water can be controlled.

To achieve the above objects, there is provided a firewood boiler, comprising a boiler body including an input port for inputting a wood fuel and a combustion air; a smoke discharge port provided on the top while being connected with a stovepipe; an air input hole provided loser to the smoke discharge port; and a hot water storing part storing a hot water; a main opening and closing unit which is installed at the boiler body so as to open and close the input port and serves to selectively supply an external air into the interior of the boiler body or cutoff the supply of the external air in a state that the input port is closed; an auxiliary opening and closing unit supplying the external air into the interior of the boiler body when the input of the external air by way of the main opening and closing unit is cutoff; a temperature sensor detecting the temperature of the hot water; and a controller controlling the input and cutoff of the air supplied by way of the main opening and closing unit based on the temperature information detected by the temperature sensor, and the hot water storing part is integrally provided on the whole portions of the boiler body, and when the input of the external air by way of the main opening and closing unit is cutoff, the external air is supplied into the interior of the boiler body by way of the auxiliary opening and closing unit, thus maintaining the seed of fire of the wood fuel.

According to an embodiment of the present invention, a firebox ceiling member is provided in the interior of the boiler body while dividing the inner space into an upper side and a lower side and crossing the interior, and the inner space of the boiler body is formed of a combustion chamber provided at a lower side of the firebox ceiling member and is configured to combust the wood fuel, and a connection passage provided at the upper side of the firebox ceiling member and connecting the combustion chamber and the smoke discharge port.

According to an embodiment of the present invention, the firebox ceiling member is installed horizontally crossing the inner space of the boiler body and has the hot water storing part in the interior of the firebox ceiling member.

According to an embodiment of the present invention, a concaved part is formed with a certain depth at the lower surface of the firebox ceiling member for the purpose of staying the heat of the combustion chamber therein, and the upper surface of the firebox ceiling member is gradually inclined in the upward direction toward the smoke discharge port.

According to an embodiment of the present invention, there is further provided a cutoff member which is formed at a boundary between the connection passage and the smoke discharge port and is installed on the ceiling of the connection passage for thereby delaying the combustion heat which is discharged to the outside by way of the connection passage.

According to an embodiment of the present invention, there is further provided a pressure adjusting member which is rotatably installed on the upper side of the boiler body so as to lower the pressure while being rotated by the pressure in the hot water storing part when the hot water stored in the hot water storing part is heated, and the pressure in the hot water storing part increases.

According to an embodiment of the present invention, the main opening and closing unit comprises a main opening and closing door which is installed in the boiler body for opening and closing the input port and has an air injection port for injecting an external air into the input port; a blower which is installed in the interior of the main opening and closing door and is drive-controlled by the controller and serves to supply the external air into the inner space of the boiler body by way of the air injection port during the operation; a ventilation port opening and closing member which is engaged to the main opening and closing door while being movable between the closing position where the air injection port is closed and the opening position where the air injection port is opened; and an opening and closing motor which is driven in response to a control signal of the controller and serves to move the ventilation port opening and closing member between the opening position and the closing position.

According to an embodiment of the present invention, the auxiliary opening and closing unit comprises an auxiliary opening and closing door which is installed at the boiler body for opening and closing the air input hole and in which a middle input port for receiving air and a middle discharge port for discharging the air are spaced apart from each other; an outer door which is engaged to the front side of the auxiliary opening and closing door and has an inner discharge port for introducing the air discharged by way of the middle discharge port into the interior of the boiler body.

According to an embodiment of the present invention, the outer input port is disposed in the lower region of the outer door, and the middle input port is disposed in the lower region of the auxiliary opening and closing door, and the middle discharge port is disposed in the upper region of the auxiliary opening and closing door, and the inner discharge port is disposed in the lower region of the inner door, so the external air is introduced into the interior of the boiler body, and the combustion gas in the interior of the boiler body is not discharged to the outside of the boiler body.

Advantageous Effects

According to the firewood boiler according to the present invention, the amount of air can be controlled by means of a control of a main opening and closing unit and an auxiliary opening and closing unit while making sure that the seed of fire can be preserved and the over combustion can be prevented.

In particular, a small amount of air can be sucked by way of an auxiliary opening and closing unit with the aid of an internal pressure in a state that the main opening and closing unit is closed, so the seed of fire can be alive long, not extinguished.

Since the seed of fire can be maintained, not extinguished, the combustion, fire extinguishing and ignition of the fuel of woods are easy to control. The disadvantage of the wood fuel can be improved, and the use of the wood fuel can be minimized, and the temperature of the stored hot water can be maintained constant. The management of the boiler is easy since the seed of fire can be maintained alive long.

In the conventional firewood boiler, though it is necessary to input wood fuels a few times per day for the sake of heating, the present invention has features in that the wood fuel can be inputted one time per day, so the combustion can be selectively performed only when it is needed, and since the seed of fire can be maintained alive long, the heated state can be maintained for one or more days even the fuel is inputted one time per day, so the maintenance is easy.

Even though the stored water is heated and the internal pressure of the hot water storing part increases, the pressure adjusting member moves by the pressure and is open, thus adjusting the pressure, so it is possible to enhance the safety by preventing explosion.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a perspective view illustrating an outer construction of a firewood boiler according to an embodiment of the present invention.

FIGS. 2 and 3 are schematic cross-sectional views to explain a combustion stop state and a combustion state of a firewood boiler of FIG. 1.

FIGS. 4 a and 4 c are views illustrating a construction of a main opening and closing part of a firewood boiler according to the present invention.

FIGS. 5 a and 5 b are views illustrating an operation state of a ventilation port opening and closing member of a main opening and closing part according to the present invention.

FIGS. 6 a and 6 c are views illustrating a construction of an auxiliary opening and closing part of a firewood boiler according to the present invention.

BEST MODES FOR CARRYING OUT THE INVENTION

The firewood according to the embodiments of the present invention will be described with reference to the accompanying drawings.

Referring to FIGS. 1, 2 and 3, the firewood boiler 1 according to an embodiment of the present invention comprises a boiler body 10, a main opening and closing unit 20 installed at a lower region of the boiler body 10, an auxiliary opening and closing unit 30 installed at an upper region of the main opening and closing unit 20, a temperature sensor 40 detecting the temperature of the stored hot water in the boiler body 10 and a controller 50 controlling the opening and closing of the main opening and closing unit 20 depending on the temperature of the stored hot water.

Here, the boiler body 10 comprises an inner space 11 for the purpose of generating heat energy by combusting the firewood in the interior. On the front side of the boiler body 10 are provided, above and below, an input port 12 for inputting firewood and an air input hole 13. At the upper side of it is provided a smoke discharge port 14 connected with a stovepipe 70. The input port 12 is provided lower than the air input hole 13 and is larger than the air input hole 13.

In addition, the boiler body 10 has a hot water storing part 15 for storing the hot water “W”. The hot water storing part 15 is integrally formed on the whole portions of the boiler body 10. The hot water stored in the hot water storing part 15 is heated by the combustion heat from the wood fuel combusted in the inner space 11 or can be supplied to a place where the heat is needed. At this time, a heating pipe “A” can be provided in the hot water storing part 15.

The hot water “W” in the hot water storing part 15 is not fully filled in the hot water storing part 15, namely, is filled with a certain marginal space 15 a left. The marginal space 15 a can be properly designed and determined. A ball top 19 a is rotatable along the moving shaft 19 b in the interior of the hot water storing part 15, thus detecting the level of the hot water “W”. An automatic water supply device 19 c starts filling hot water in accordance with the water level detected by the ball top 19 a. The automatic water supply device 19 c is connected with a water supply line (not shown).

An air input hole 13 is formed closer to the smoke discharge port 14. The air input hole 13 is configured to supply a minimum amount of the external air by way of the auxiliary opening and closing unit 30 so that the seed of fire cannot extinguish in the inner space 11 in a state that the input port 12 is fully closed.

A pressure adjusting member 60 is installed at the top of the boiler body 10 so as to discharge the pressure of the hot water storing part 15 to the outside so as to prevent an explosion of the boiler body 10 when the hot water “W” of the hot water storing part 15 is heated, and the internal pressure increases. The pressure adjusting member 60 is rotatably installed at the pressure discharge port 16 formed at the top of the boiler body 10. It is preferred that when the generating pressure exceeds a certain level, the pressure adjusting member 60 is forcibly rotated by the pressure when a certain level of pressure generates, and the pressure is discharged to the outside. When the pressure drops below a certain level, it returns by means of the self-weight, thus closing the pressure discharge port 16.

Since the pressure adjusting member 60 is configured so that it can return by its self-weight, the errors and operation defects do not occur even when it is exposed long to vapor during the use. In other words, in case that a safety value used at the pressure tank or the like is installed, since the hot water “W” is water, the vapor valve is exposed to the vapor during the use and is oxidized, so it becomes a cause of the errors. In this case, the pressure is not properly adjusted, which results in an increased chance of explosion. In the present invention, the installation of the pressure adjusting member 60 helps protect the boiler body 10 in safe from the danger of explosion while preventing a high risk of accidents.

The inner space 11 of the boiler body 10 is divided into a combustion chamber 11 a of a lower side and a connection passage 11 b of an upper side. A firebox ceiling member 17 is installed in the interior of the boiler body 10 so as to divide the combustion chamber 11 a and the connection passage 11 b. The firebox ceiling member 17 is horizontally installed in the interior of the boiler body 10 so as to partition the inner space 11 into the upper and lower sides and has a hot water storing part 15. At the lower side of the firebox ceiling member 17 is provided a combustion chamber 11 a so as to combust the wood fuel, and at the upper side of the firebox ceiling member 17 is provided a connection passage 11 b connecting the combustion chamber 11 a and the smoke discharge port 14.

The firebox ceiling member 17 has a lower surface which is concaved in a certain depth, and in the combustion chamber 11 a is provided a concave part 17 a to allow the heat, namely, the heat energy generating during the combustion to gather. The upper surface of the firebox ceiling member 17 is a slope surface 17 b which is gradually inclined in the upward direction toward the smoke discharge port 14. The width of the connection passage 11 b gradually decreases in the direction from the end portion of the firebox ceiling member 17 to the smoke discharge port 14. In addition, at the end portion of the connection passage 11 b are provided the smoke discharge port 14 and the air input hole 13. Thanks to the formation of the slope surface 17 b, the pyroligneous liquor generating in the combustion chamber 11 a and moving along the connection passage 11 b is forced to flow to the combustion chamber 11 a along with soot for the sake of re-combustion. So, the efficiency of the fuel can be enhanced, and it is possible to prevent any inconvenience of the user which might occur since the pyroligneous liquid is discharged to the outside of the boiler.

In addition, the productions of the pyroligneous liquid and soot can be minimized and the contamination in the interior of the stovepipe 70 can be prevented, so the maintenance cost and labor force needed to clean the inner side of the boiler body 10 and the stovepipe 70 can be saved, thus reducing the maintenance costs.

A plurality of interfering rods “B” are provided in the interior of the concave part 17 a so as to increase the staying time of the flame in the interior of the combustion chamber 11 a in such a way to delay the movements of the flame generating as fuel is combusted. As shown in FIG. 3, the flame spreads over the interfering rods “B” as it is blocked by the interfering rods “B”, so the staying time of the flame in the interior of the combustion chamber 11 a extends, whereby the heat transfer surface area to which is transferred heat, increases, thus enhancing the returning ratio of the combustion heat.

Most of the heat generating during the combustion in the combustion chamber 11 a stays in the concaved part 17 a of the lower side of the firebox ceiling member 17, thus fully heating the firebox ceiling member 17, and the cooled heat moves in the direction of the arrow of FIG. 3 and is discharged to the discharge port 14 by way of the connection passage 11 b.

At this time, the cut-off member 18 is installed at the boundary between the connection passage 11 b and the smoke discharge port 14 so as to secondarily combust the combustion gas which was not firstly combusted as it stays in the connection passage 11 b for a second. The cut-off member 18 is installed on the ceiling of the connection passage 11 b, so the combustion gas and heat moving by way of the connection passage 11 b can stay in a high temperature state while supplying oxygen to the combustion gas, thus burning the pyroligneous liquor with the aid of the second combustion, and what the heat energy is discharged to the smoke discharge port 14 is delayed, thus enhancing the heat efficiency.

FIGS. 4 a to 4 c are perspective, cross-sectional and schematic views illustrating the constructions of the main opening and closing unit 20 of the firewood boiler 1 according to the present invention.

As shown therein, the main opening and closing unit 20 is installed at an outer side of the boiler body 10 in such a way to open and close the input port 12. The main opening and closing unit 20 is opened and closed in response to the control of the controller 50 and controls the supply of oxygen into the interior of the boiler body 10. The main opening and closing unit 20 comprises a main opening and closing door 21, an engaging plate 23 engaged to an inner side of the main opening and closing door 21, a ventilation port opening and closing member 24 for selectively opening and closing a second air injection port 22 a, a blower 25 for supplying oxygen by way of the second air injection port 22 a, and an opening and closing motor 27 driving the ventilation port opening and closing member 24.

The main opening and closing door 21 is rotatably installed at an outer side of the boiler body 10 in such a way to selectively open and close the whole portions of the input port 12. The main opening and closing door 21 has a first air injection port 21 a for injecting an external air into the input port 12, and a space in which are installed the blower 25, the ventilation port opening and closing member 24 and the opening and closing motor 27.

The main opening and closing door 21 is installed in such a way to maintain the closed state of the input port 12 in safe by means of a double-locking system (not shown). When the wood fuel is inputted into the combustion chamber 11 a, the input port 12 is opened by rotating the main opening and closing door 21.

At an outer surface of the main opening and closing doo 21 is provided a first air injection port 21 a for injecting an external air, and at an inner surface of the man opening and closing door 21 is provided a second air injection port 22 a for injecting the air from the first air injection port 21 a into the interior of the boiler body 10.

The air introduced into the second air injection port 22 a flows into the boiler body 10 by way of the air discharge port 23 a disposed at the engaging plate 23 engaged to the inner side of the main opening and closing door 21.

The blower 25 is installed in the interior of the main opening and closing door 21, and during the operation, the external air is supplied to the interior of the combustion chamber 11 a by way of the air injection ports 21 a, 22 a and 23 a. The blower 25 is configured to stop and start operating in response to a driving signal from the controller 50. As the blower 25 is driven, when an external air is supplied to the combustion chamber 11 a, the wood fuel in the combustion chamber 11 a receives an external air and maintains a combustion state, thus generating combustion energy. When the blower 25 stops, the second air injection port 22 a is closed by the ventilation port opening and closing member 24, so the external air is not supplied. In this case, the wood fuel in the combustion chamber 11 a is not combusted.

At the main opening and closing door 21 is installed the ventilation port opening and closing member 24 for the purpose of selectively opening and closing one among the air injection ports 21 a, 22 a and 23 a disclosed closer to the main opening and closing door 21, preferably, the air injection port 22 a disposed at the middle of them.

As shown in FIGS. 5 a and 5 b, the ventilation port opening and closing member 24 is rotatable by means of the opening and closing motor 27. The ventilation port opening and closing member 24 is movably disposed between the closing position (the state of FIG. 5 b) where the second air injection port 22 a is closed and the opening position (the state of FIG. 5 a) where the second air injection port 22 a is opened.

The opening and closing port 24 a provided in position alignment with the second air injection port 22 a passes through the surface of the ventilation port opening and closing member 24. The ventilation port opening and closing member 24 rotates to the opening position so that the opening and closing port 24 a and the second air injection port 22 a are aligned by means of the opening and closing motor 27 when the air is introduced into the interior of the boiler body 10. So, the air becomes communicated and it becomes movable.

When the input of the air is cutoff, as shown in FIG. 5 b, the ventilation port opening and closing member 24 rotates to the closing position by means of the opening and closing motor 27, and the positions of the opening and closing port 24 a and the second air injection port 22 a become deviated, thus closing the ventilation port 22 a. So, the input of the air into the interior of the boiler body 10 is cutoff.

The opening and closing motor 27 is formed of a driving motor which drives the ventilation port opening and closing member 24 to move to between the opening position and the closing position. The opening and closing motor 27 is configured to operate or stop in response to a control signal from the controller 50, so the second air injection port 22 a can be opened or closed.

When the ventilation port opening and closing member 24 is installed to slide, the opening and closing motor 27 might be a solenoid or a hydraulic cylinder unit, instead of the bidirectional driving motor. It is obvious that various driving devices might be adapted.

A packing member 22 is provided in the engaging region of the main opening and closing door 21 and the engaging plate 23 the sake of sealing.

FIGS. 6 a to 6 c are perspective, disassembled and cross-sectional views illustrating a construction of the auxiliary opening and closing unit 30 according to the present invention.

The auxiliary opening and closing unit 30 is configured to keep the seed of fire alive in such a way to supply a minimum amount of air into the interior of the boiler body 10 when the input of the air into the boiler body 10 is closed by means of the main opening and closing unit 20.

The auxiliary opening and closing unit 30 comprises an auxiliary opening and closing door 31 installed in an opening and closing way at the input hole 13, an outer door 32 installed at an outer side of the auxiliary opening and closing door 31, and an inner door 34 installed at an inner side of the auxiliary opening and closing door 31.

At both walls of the auxiliary opening and closing door 31 are provided a middle input port 31 a for receiving air from the outer door 32, and a middle discharge part 33 a for discharging the air introduced into the middle input port 31 a.

At the plate surface of the outer door 32 is provided an outer input port 32 a for receiving an external air, and at the plate surface of the inner door 34 is provided an inner output port 34 a for discharging the air, which passed through the auxiliary opening and closing door 31, into the interior of the boiler body 10.

Here, the outer input port 32 a and the middle input port 31 a are provided in the lower region of the auxiliary opening and closing door 31, and the middle discharge part 33 a is provided in the upper region of the auxiliary opening and closing door 31, and the inner output port 34 a is provided in the lower region.

As indicated by the arrow, the air flow passage ranging from the outer side to the inner side is arranged, above and below, in a zigzag shape, so the external air can be naturally inputted by means of a suction pressure of the inner side of the boiler body 10; however the combustion gas in the boiler body 10 is not discharged to the outside.

As the auxiliary opening and closing unit 30 is installed, the input port 12 is closed by means of the main opening and closing unit 20. In a state that the supply of the external air by way of the input port 12 is disconnected, a minimum amount of the external air can be supplied to the combustion chamber 11 a by way of the air input hole 13 and the connection passage 11 b. In a state that the input port 12 is closed, the wood fuel is not combusted, and a minimum amount of external air is supplied by way of the air input hole 13, so the seed of the fire of the wood fuel which is combusted in the combustion chamber 11 a is not extinguished and can remain alive long.

The temperature sensor 40 is installed so as to detect the temperature of the hot water “W” stored in the hot water storing part 15 of the boiler body 10. The information detected by the temperature sensor 40 is transferred to the controller 50.

The controller 50 controls the supply and the cutoff of the supply of the external air to the combustion chamber 11 a by way of the main opening and closing unit 20. When the supply of the external air by way of the main opening and closing unit 20 is cutoff, a minimum amount of air can be supplied to the interior of the boiler body 10, namely, the combustion chamber 11 a by way of the auxiliary opening and closing unit 30, so the seed of fire can survive long in the extinguished state of the firewood in the combustion chamber 11 a.

When the temperature detected by the temperature sensor 40 lowers below the reference temperature, the controller 50 controls the opening and closing motor 27 so as to open the second injection hole 22 a, and it is controlled that the external air can be inputted into the combustion chamber 11 a by way of the input port 12 by driving the blower 25, so the power of fire of the wood fuel can be raised, and the wood fuel is combusted until the hot water “W” reaches the reference temperature.

When the temperature detected by the temperature sensor 40 reaches the reference temperature, the controller 50 stops the operation of the blower 25 and closes the air input hole 13 by controlling the opening and closing motor 27, so the supply of the external air by way of the input port 12 is cutoff.

At this time, the suction force is generated owing to the lack of the oxygen in the interior of the combustion chamber 11 a, and the oxygen introduced into the interior by way of the auxiliary opening and closing unit 30 spreads toward the combustion chamber 11 a. The combustion of the wood fuel in the combustion chamber 11 a stops, and the heat energy is no longer generated. The seed of fire in the combustion chamber 11 a can survive long with the aid of a minimum amount of external air supplied by way of the auxiliary opening and closing unit 30. So, when a lot of an external air is supplied by way of the input port 12 in the state of seed, the combustion starts again. The combustion and extinguishing can be easily controlled even when uses the wood fuel. It is possible to prevent an unnecessary consumption of the fuel.

INDUSTRIAL APPLICABILITY

According to the firewood according to the present invention, the amount of air can be controlled by controlling the main opening and closing unit and the auxiliary opening and closing unit, and the seed of fire can remain alive while making sure that there is not an over combustion.

In particular, a minimum amount of external air can be sucked by way of the auxiliary opening and closing unit with the aid of the internal pressure in a state that the main opening and closing unit is closed, so the seed of the fire can survive long.

Since the seed of the fire can survive, the combustion, extinguishing and ignition of the wood fuel can be easily controlled. So, it is possible to keep constant the temperature of the hot water while overcoming the limited characteristics of the wood fuel and minimizing the use of the wood fuel. Since the seed of the fire can survive long, the management of the boiler is easy, and the present invention is well applicable in the industry.

[Descriptions of the reference numerals]  1: firewood boiler 10: boiler body 11a: combustion chamber 11b: connection passage 12: input port 13: air input hole 14: smoke discharge port 17: firebox ceiling member 17a: concaved part 17b: slope surface 18: cutoff member 19a: ball top 19b: moving shaft 19c: automatic water supply device 20: main opening and closing unit 21: main opening and closing door 21a: first air injection port 22: packing member 22a: second air injection port 23: engaging plate 23a: air discharge port 24: ventilation port opening and closing member 24a: opening and closing port 25: blower 27: opening and closing motor 30: auxiliary opening and closing unit 31: auxiliary opening and closing door 31a: middle input port 31b: middle discharge port 32: outer door 32a: outer input port 33: packing 34: inner door 34a: inner output port 40: temperature sensor 50: controller 60: pressure adjusting member 70: stovepipe 

1. A firewood boiler, comprising: a boiler body including: an input port for inputting a wood fuel and a combustion air; a smoke discharge port provided on the top while being connected with a stovepipe; an air input hole provided loser to the smoke discharge port; and a hot water storing part storing a hot water; a main opening and closing unit which is installed at the boiler body so as to open and close the input port and serves to selectively supply an external air into the interior of the boiler body or cutoff the supply of the external air in a state that the input port is closed; an auxiliary opening and closing unit supplying the external air into the interior of the boiler body when the input of the external air by way of the main opening and closing unit is cutoff; a temperature sensor detecting the temperature of the hot water; and a controller controlling the input and cutoff of the air supplied by way of the main opening and closing unit based on the temperature information detected by the temperature sensor, and the hot water storing part is integrally provided on the whole portions of the boiler body, and when the input of the external air by way of the main opening and closing unit is cutoff, the external air is supplied into the interior of the boiler body by way of the auxiliary opening and closing unit, thus maintaining the seed of fire of the wood fuel.
 2. The boiler of claim 1, wherein a firebox ceiling member is provided in the interior of the boiler body while dividing the inner space into an upper side and a lower side and crossing the interior, and the inner space of the boiler body is formed of a combustion chamber provided at a lower side of the firebox ceiling member and is configured to combust the wood fuel, and a connection passage provided at the upper side of the firebox ceiling member and connecting the combustion chamber and the smoke discharge port.
 3. The boiler of claim 2, wherein the firebox ceiling member is installed horizontally crossing the inner space of the boiler body and has the hot water storing part in the interior of the firebox ceiling member.
 4. The boiler of claim 2, wherein a concaved part is formed with a certain depth at the lower surface of the firebox ceiling member for the purpose of staying the heat of the combustion chamber therein, and the upper surface of the firebox ceiling member is gradually inclined in the upward direction toward the smoke discharge port.
 5. The boiler of claim 2, further comprising: a cutoff member which is formed at a boundary between the connection passage and the smoke discharge port and is installed on the ceiling of the connection passage for thereby delaying the combustion heat which is discharged to the outside by way of the connection passage.
 6. The boiler of claim 2, further comprising: a pressure adjusting member which is rotatably installed on the upper side of the boiler body so as to lower the pressure while being rotated by the pressure in the hot water storing part when the hot water stored in the hot water storing part is heated, and the pressure in the hot water storing part increases.
 7. The boiler of claim 1, wherein the main opening and closing unit comprises: a main opening and closing door which is installed in the boiler body for opening and closing the input port and has an air injection port for injecting an external air into the input port; a blower which is installed in the interior of the main opening and closing door and is drive-controlled by the controller and serves to supply the external air into the inner space of the boiler body by way of the air injection port during the operation; a ventilation port opening and closing member which is engaged to the main opening and closing door while being movable between the closing position where the air injection port is closed and the opening position where the air injection port is opened; and an opening and closing motor which is driven in response to a control signal of the controller and serves to move the ventilation port opening and closing member between the opening position and the closing position.
 8. The boiler of claim 1, wherein the auxiliary opening and closing unit comprises: an auxiliary opening and closing door which is installed at the boiler body for opening and closing the air input hole and in which a middle input port for receiving air and a middle discharge port for discharging the air are spaced apart from each other; an outer door which is engaged to the front side of the auxiliary opening and closing door and has an inner discharge port for introducing the air discharged by way of the middle discharge port into the interior of the boiler body.
 9. The boiler of claim 8, wherein the outer input port is disposed in the lower region of the outer door, and the middle input port is disposed in the lower region of the auxiliary opening and closing door, and the middle discharge port is disposed in the upper region of the auxiliary opening and closing door, and the inner discharge port is disposed in the lower region of the inner door, so the external air is introduced into the interior of the boiler body, and the combustion gas in the interior of the boiler body is not discharged to the outside of the boiler body. 